's nominee for head of homeland security. he wound up pleading guilty to tax evasion. in line to the white house. spending three years in a federal minimum security prison. earlier this week, he spoke to matt lauer days after being relieved from house arrest. he opened up about what he realized about life behind bars and his new mission now that he's out. >> bernie, you spent six years of your life running that jail over our shoulder there which is one of the biggest and most notorious jails in the country. when you look back at that place now, does your perspective change? >> yeah, it changes. when i ran that system, i focused on the day-to-day operations of care, custody, and control. what i realized today is, especially in the federal prison system, that's not necessarily the focus. >> reporter: despite a long and impressive resume in law enforcement, kerik says only a few months after behind bars himself that he realized that criminal justice system was broken. >> these young men, first-time nonviolence low level drug offense their sentence may be five or ten years, but you know what?